1. Field of the Invention
The present invention concerns a method for planning an examination of an examination subject in a magnetic resonance system, wherein images of different regions of the examination subject are acquired. The invention is particularly (but not exclusively) applied in magnetic resonance systems in which images of the examination subject are acquired at different table positions.
2. Description of the Prior Art
In magnetic resonance systems the trend has emerged toward ever-shorter magnet shapes in order to increase the comfort for the patient in the examination. In most examinations these shorter magnet shapes enable the head of the patient to not be enclosed by the magnet, so that the examination subject does not experience claustrophobic discomfort.
Such shorter magnets lead to the available field of view in the acquisition becoming ever smaller. In MR examinations the relevant image section of the examined body region likewise becomes ever smaller. It is simultaneously ever more difficult for the operator to cover (image) larger examination regions with only one examination.
Furthermore, MR techniques have been developed with which a larger region of the body can be examined, by shifting (displacing) the table on which the examined person rests through the magnets, so examinations are conducted at multiple table positions. Examination of regions of the body that are larger than the field of view available to the system are thereby possible.
According to the prior art, a body region that is larger than the available field of view is examined by data being acquired from a number of slabs or levels. The body region is thus deconstructed into individual segments, and a measurement protocol that can include a number of imaging sequences is implemented at an associated table position in each segment. For example, the entire body can be acquired by measurements at different body regions, this ensues at different slabs (table positions or imaging regions). The images that are acquired at each slab respectively have measurement parameters (such as, for example, echo time, repetition time, slice thickness, number of the slices, voxel size, slice orientation etc.) that are independent of one another. The problem now is that the operator has no possibility to establish a dependency between the individual slabs or the measurement protocol parameters. For example, if the operator changes the contrast at the third level of a whole-body examination, this contrast change is not automatically transferred to the measurements of the other slabs. When the individual images should be assembled into an overall image, however, specific parameters for all images must be the same so that, for example, images with various contrast ratios are not contained in the composite image. According to the prior art, in the case of parameter changes that should apply for entire multi-level examinations, the operator would previously have to adjust the individual parameter data sets manually for each level. The operator would consequently note each parameter change, open the measurement protocol for the next slab for processing and individually adjust each measurement parameter or each data post-processing step.